A future that runs on hydrogen looks a little more likely thanks to a device that uses common materials to make the clean fuel from sunlight and water. The proof-of-concept gadget points to a cheap and efficient way of producing hydrogen fuel to power cars or generate electricity. Researchers want to find an easy way to make hydrogen gas because it packs as much energy per pound as a gallon of gasoline. Hydrogen fuel cells can generate electricity for power or propulsion. A fuel cell electric vehicle can operate at two to three times the efficiency of a vehicle powered by a traditional internal combustion engine. Moreover, the fuel cells produce only water vapor as exhaust. But the current method of making hydrogen from fossil fuels is energy intensive and negates some of the environmental benefits.